MODELING OF SOLID FLOW IN MOVING BEDS

Solid descending flow due to gravity is frequently applied to industri al processes. Several kinds of models have been proposed like the plug flow model, the potential flow model, the kinematic model, etc. In th is study, a viscous flow model based on the Navier-Stokes equation has been developed and was compared with the potential flow and the kinem atic models. Both two and three dimensional experimental apparatuses h ave been constructed to observe the velocity fields. The concept of so lid viscosity was quoted to describe the friction between particles an d the value was obtained from the experimental data. Slip boundary con dition was used at the wall and the friction between particles and the wall or the dead zone was expressed by the Fanning equation. Navier-S tokes equation was applied to simulate the solid flow. The good agreem ent between the observed and computed results was obtained in differen t scale apparatuses at different solid descending velocities. The comp utation results gave about 0.07 Pa.s as the solid viscosity of sand pa rticles with the diameter of 0.001-0.002m. The solid-gas countercurren t flow was also simulated by the Navier-Stokes equation with the same value of solid viscosity.